I have an 03 Heritage, with about 6k miles, and have owned it for about 4 months. (my first Harley) I have put about 3k miles on it and really love the bike. It rides great, looks great, and runs great...EXCEPT..... an occasional annoying backfire thru the carb! It seems to happen most often after a highway run during cold or cool weather. I stop at a lite at the end of an exit, then as I accelerate POP thru the carb. Sometimes more than once. The bike was essentially a garage ornament for the orig. owner, I bought it with less than 3k miles on it. I recently had the dealer do a 5K checkup, including a sparkplug change. When I asked about the Backfiring I was told its normal, they all do it! BS I say!! Anybody have any words of wisdom?? I am planing a trip to the Keys after Christmas, hate to have problems.

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It sounds like your slow-speed jetting is too lean. It's most noticeable when it's cold. I had that problem, and once I had the carb rejetted, and it went away.

Cheers!
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had the same problem on my 05. after a basic service it stopped. maybe coincedence? not sure.

 

My Outlaw backfired once in awhile, but it was the lean condition of having the a/c off to get it started, and some really crap gas. Once I cleaned it all out and put the K&N back on, no more backfire.

 

i bought my flht used, had after market slip-ons,never been re-jetted. i pulled the plugs they were showing lean. had it re-jetted (low speed) and dyno'd-problem solved.

 

sound like the mixture screw was never turned out to richen up the idle mixture

 

Colder temps the air is denser. It takes longer for the bike to get to OT (operating temp). denser air at cold temp means the bike has leaned out. It will back fire thru the carb. pull out the enricher part way.